For the purpose of, for example, vividifying an image obtained by image sensing of an object with an imaging device, a spatial product sum calculation (a convolution) is performed for each picture element data of one frame which is a candidate for processing.
FIG. 7 is a diagram explanatory of a spatial product sum calculation with 3 rows and 3 columns. Where picture element data Fi,j and load coefficients Wi,j are arranged as shown, the result calculated of the spatial product sum, G2,2, for picture element data F2,2 is given by the following equation: ##EQU1## For convenience of description, calculations W1,1.times.F1,1+W2,1.times.F2,1+W3,1.times.F3,1, W1,2.times.F1,2+W2,2.times.F2,2+W3,2.times.F3,2, and W1,3.times.F1,3+W2,3.times.F2,3+W3,3.times.F3,3 in Eq. (1) will hereinafter be referred to as first, second and third calculations, respectively.
Conventionally, such a spatial product sum calculation as mentioned above is conducted through use of, for example, such devices as shown in FIGS. 8 and 9. The device depicted in FIG. 8 comprises one multiplier 1 and one integrator 2, in which the data Fi,j and the load coefficient Wi,j are sequentially entered into the one and the other input of the multiplier 1 to obtain Fi,j.times.Wi,j and the results of a total of nine calculations are integrated by the integrator 2.
The device shown in FIG. 9 comprises a total of nine multipliers 3.sub.1 to 3.sub.g and one adder 4, in which the multipliers receive the data Fi,j at one input and the different load coefficients Wi,j at the other input and perform parallel processing, the results of which are added together by the adder 4.
The device shown in FIG. 8 is small in the number of parts used, but requires much time for the spatial product sum calculation for each picture element data, and hence it is not suited for the calculation of the spatial product sums of, for example, 256.times.256 picture elements.
The unit depicted in FIG. 9 is capable of calculating the spatial product sum of each picture element data at a speed around nine times higher than the above device, but employs as many as nine bulky and expensive multipliers, and hence it is inevitably costly and large-sized, in general.